From 8661e263404f33895be8bbe420d544f4f910af3f Mon Sep 17 00:00:00 2001
From: Matthew Garrett <mjg59@srcf.ucam.org>
Date: Thu, 8 Mar 2012 10:35:59 -0500
Subject: [PATCH 04/16] x86: Lock down IO port access when securelevel is
enabled
Patch-mainline: Queued in subsystem maintainer repository
Git-repo: https://github.com/mjg59/linux
Git-commit: 8661e263404f33895be8bbe420d544f4f910af3f
References: fate#320387
IO port access would permit users to gain access to PCI configuration
registers, which in turn (on a lot of hardware) give access to MMIO register
space. This would potentially permit root to trigger arbitrary DMA, so lock
it down when securelevel is set.
Signed-off-by: Matthew Garrett <mjg59@srcf.ucam.org>
Acked-by: Lee, Chun-Yi <jlee@suse.com>
---
arch/x86/kernel/ioport.c | 5 +++--
drivers/char/mem.c | 7 +++++++
2 files changed, 10 insertions(+), 2 deletions(-)
--- a/arch/x86/kernel/ioport.c
+++ b/arch/x86/kernel/ioport.c
@@ -15,6 +15,7 @@
#include <linux/thread_info.h>
#include <linux/syscalls.h>
#include <linux/bitmap.h>
+#include <linux/security.h>
#include <asm/syscalls.h>
/*
@@ -28,7 +29,7 @@ asmlinkage long sys_ioperm(unsigned long
if ((from + num <= from) || (from + num > IO_BITMAP_BITS))
return -EINVAL;
- if (turn_on && !capable(CAP_SYS_RAWIO))
+ if (turn_on && (!capable(CAP_SYS_RAWIO) || (get_securelevel() > 0)))
return -EPERM;
/*
@@ -108,7 +109,7 @@ SYSCALL_DEFINE1(iopl, unsigned int, leve
return -EINVAL;
/* Trying to gain more privileges? */
if (level > old) {
- if (!capable(CAP_SYS_RAWIO))
+ if (!capable(CAP_SYS_RAWIO) || (get_securelevel() > 0))
return -EPERM;
}
regs->flags = (regs->flags & ~X86_EFLAGS_IOPL) |
--- a/drivers/char/mem.c
+++ b/drivers/char/mem.c
@@ -27,6 +27,7 @@
#include <linux/export.h>
#include <linux/io.h>
#include <linux/uio.h>
+#include <linux/security.h>
#include <linux/uaccess.h>
@@ -559,6 +560,9 @@ static ssize_t read_port(struct file *fi
unsigned long i = *ppos;
char __user *tmp = buf;
+ if (get_securelevel() > 0)
+ return -EPERM;
+
if (!access_ok(VERIFY_WRITE, buf, count))
return -EFAULT;
while (count-- > 0 && i < 65536) {
@@ -577,6 +581,9 @@ static ssize_t write_port(struct file *f
unsigned long i = *ppos;
const char __user *tmp = buf;
+ if (get_securelevel() > 0)
+ return -EPERM;
+
if (!access_ok(VERIFY_READ, buf, count))
return -EFAULT;
while (count-- > 0 && i < 65536) {